Granulate Production in a Single-Pot Process - Pharmaceutical Technology
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Granulate Production in a Single-Pot Process

Horizontal single-pot device for production (source: Lödige)

Most medication is taken orally and pressed into tablet shape for ease of use. In order to ensure reliable production of pharmaceuticals with optimal and reproducible quality levels, the raw materials are processed into free-flowing granules. Granulation involves various essential process steps such as mixing, liquid addition, accretion of granules and drying. The single-pot method developed by Lödige allows all of these steps to be performed in a single system, saving space, time and money.

Powdered raw materials for pharmaceutical formulations may have inadequate flow properties due to small particle sizes. For this reason, granulation is used to optimise the properties of raw materials. An individual granule consists of several powder particles. For pharmaceutical applications, the range of particle sizes for granules is between 0.05mm and 2mm.

The benefits associated with granulation are:

  • Avoidance of disintegration effects thanks to stable mixtures
  • Dust-free transport and simple dosing thanks to improved flow properties
  • Improved properties in terms of tablet compression
  • Targeted release of active ingredients, including by modifying the granulation route
  • Optimal solubility, including by avoiding clumping during dissolution
  • Improved stability for storage purposes by reducing the surface area of the product
  • Precise reproducibility, minimising differences between batches

In principle, the complete granulation process is divided into mixing, granule accretion and drying steps, followed by steps such as sieving or addition of flow promoters.

Wet granulation in a single-pot method

Granulation typically occurs through the constant binding of particles via a bridge. Agglomeration or granulation of powders in pharmaceutical applications is generally achieved through wet or dry granulation. The choice of method will depend on the raw materials, the application field and the properties required of the end product. Other important parameters also need to be considered, such as processing time, product temperature stress etc.

Production facilities often make use of wet granulation by means of a vertical high-shear mixer and a fluid bed dryer downstream. This process makes it necessary to transport the granulated matter into a separate fluid bed dryer for drying. Separate systems are therefore required for granulation and drying. Potential implications include additional space requirements, elaborate explosion protection concepts and possible damage to the sensitive goods for drying during transport.

The single-pot wet granulation system developed by Lödige is an effective solution for avoiding these disadvantages. During single-pot granulation in the horizontal vacuum shovel dryer, all process steps ‒ mixing of powder, wet granulation and drying ‒ take place in a single device with a horizontal mixing shaft. This combines the benefits of the drying process with the technical possibilities offered by a horizontal Ploughshare® Mixer, which ensures production with maximum mixing accuracy.

Thanks to the double jacket, the device can accommodate the drying of the product with an energy input following granulation. The transfer of the product to a second device is no longer necessary, which saves time and space and also avoids potential product faults due to stress endured by the still sensitive material for drying.

The mixing tools of the horizontal vacuum shovel dryer also provide essential support for the drying process by carrying out a steady exchange between the product and heat transfer surface. This ensures a very effective heat transfer into the moist product. Compared to alternative vertically arranged drying systems, the horizontal dryer has a significantly higher available heat exchange surface, which also leads to shorter drying times.

The drying process is supplemented by the option of operating in a vacuum. As this reduces the boiling point, it decreases the temperature stress on the product and accelerates the extraction of any vapours generated. This helps ensure efficient and gentle drying, even for sensitive products. This single-pot method is perfect for producing, for instance, granules for effervescent tablets or vitamin C powder.

The advantages of the single-pot solution at a glance:

  • Compact and economical equipment
  • Short processing times
  • Energy-efficient process compared with, for example, fluid bed spray agglomeration

All Lödige machines are tailored to customer requirements, so the single pot solution can be adapted perfectly to the production process in question.

Contact for reader inquiries:

Dominik Sander
Gebr. Lödige Maschinenbau GmbH
Elsener Straße 7-9
D-33102 Paderborn

Phone: +49-5251-309-159


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